This is kind of a patch job where you still have to use gas.
It doesn't have and electric only mode as described.
He did say it was built around the brakes but then wouldn't there
be heating problems with the brakes .
He did not mention regenerative brake charging.
I think a nat gas conversion makes more sense than this.

Seems like a plausible retrofit to a FWD daily driver city vehicle. (200 more ft# in a MINI, anyone?)

Casual googling reveals a target price of $3K for the system. At $4.50 a gallon for premium in LA, that's equivalent to ~700 gallons of gas, or 40 tankfulls, or a year of driving. Conclusion: it pays foritself in savings over two years, if it really does double your mileage as per the claim. Plus you get the tax benefits and other perks - carpool lane access, etc. That's a win, if they hit the price point & performance numbers.